I don't have AC but a single pipe that drips, what the heck is that drip from?

I don't have AC but a single pipe that drips, what the heck is that drip from?

Check to see if it is the TPV valve from your hot water heater. You should see a line from the heater going outdoors. It could be a bad valve or the PRV could be allowing too much pressure. Need to have someone measure house pressure.

Hi kibs and Welcome to The Plumbing Page at AMHD.com. You're responding to a 4 year old dead threads so I gave you one of your own. Please check the date before you post. Thanks
Are you on a well or city water? What is your house pressure? Is there a PRV installed? What material is the pipe? If you shut the water off to the water heater will the pipe still trip? Let me know. Back to you, Tom

It can be an overflow line from ANY pressurized tank in your house - not only A/C unit - like hot water heater, steam generator, etc - or from any drip pan in your house

Is it a continuous leak ?

Back to you / Milo